1. Field of the Invention
This invention relates to overrunning coupling assemblies and, in particular, to overrunning coupling assemblies having improved shift feel and/or noise reduction.
2. Background Art
Overrunning coupling assemblies are used for transferring torque from a driving member to a driven member in a variety of structural environments. This permits the transfer of torque from a driving member to a driven member while permitting freewheeling motion of the driving member relative to the driven member when torque is interrupted.
For purposes of this disclosure, the term coupling should be interpreted to include clutches or brakes wherein one of the plates is drivably connected to a torque delivery element of a transmission and the other plate is drivably connected to another torque delivery element or is anchored and held stationary with respect to a transmission housing. The terms coupling, clutch and brake may be used interchangeably.
A pocket plate may be provided with angularly disposed recesses or pockets about the axis of a one-way clutch. The pockets are formed in the planar surface of the pocket plate. Each pocket receives a torque transmitting pawl or strut, one end of which engages an anchor point in a pocket of the pocket plate. An opposite edge of the strut, which may hereafter be referred to as an active edge, is movable from a position within the pocket to a position in which the active edge extends outwardly from the planar surface of the pocket plate. The struts may be biased away from the pocket plate by individual springs.
A notch plate may be formed with a plurality of recesses or notches located approximately on the radius of the pockets of the pocket plate. The notches are formed in the planar surface of the notch plate.
Pawl-type clutches inherently have shift bump issues. Impact loading is described from the following formula:F*t=m*V.Stated in words: average force multiplied by impact time equals mass multiplied by change in velocity. If one could somehow increase the time, there would be a corresponding decrease in force at time of impact.
U.S. Pat. Nos. 5,852,932; 6,032,774; and 6,745,880 show the use of a wave spring to assist a pawl or strut into a locked position. For example, U.S. Pat. No. 5,852,932 show such an arrangement as well as the use of a compression spring to absorb shock in a circumferential direction.
U.S. Pat. Nos. 6,745,880; 6,032,774; and 5,852,932 also show a wave spring utilized to assist a strut or pawl into a locked position. For example, the prior art wave spring of the '932 patent engages a “drive dog” style clutch.
The '774 patent discloses the combination of a drive dog and a ratcheting style one-way clutch (i.e., OWC) in combination with a wave ring. The wave ring disengages the dog style clutch.
The wave spring of the '880 patent is used to bias a controllable mechanism which is attached to a roller system.
U.S. Pat. No. 6,125,980 discloses an overrunning coupling assembly including a snap ring or retainer device.
U.S. Pat. No. 6,193,038 discloses a one-way clutch including a retaining device such as a weir or snap ring disposed in a groove defined by first and second members of an outer plate assembly.
U.S. Pat. No. 6,290,044 discloses a selectable one-way clutch assembly including a weir plate installed in a groove of a drum to absorb forces.
However, a need still exists for an overrunning coupling assembly which addresses shift bump issues to thereby improve shift feel and/or noise reduction.